The 2011 Child Labour Index compiled by the risk analysis firm Maplecroft has illustrated the scale of the global child labour problem, with 68 countries ranked as being of “extreme risk” due to the level of abuse.

A number of UK high-street retailers, including Primark and Monsoon, have been caught up in recent exposés of labour practices through rogue suppliers.

Child workers are most frequently employed in clothing manufacturing, and Maplecroft says 70% of them work in the countryside, making them harder to trace.

India, the worst rated of the vaunted Bric economies, scored zero, as it did last year. Its government figures suggest it has up to 16.4 million child labourers – although the US state department puts that figure closer to 55 million.

The problem is most marked in agriculture, including hybrid seed production, where Unicef says private companies employ 200,000 children in Andhra Pradesh alone.